Overview

One of the fundamental features of geochemistry is that it deals with "open
systems". Open systems usually go to "steady state" rather than chemical equlibrium. To predictthe chemistry of a system at steady state, we need to understand the rates of chemical reactions relative to the fluxes in and out of the system.

Objectives

You should be able to outline:

the concepts of flux, reservoir and residence time.

the concept of steady state vs. chemical equilibrium

Ficks first and second laws

the origin of chemical gradients in terms of the competition between
fluxes and reaction rates.